Precise arraying of perovskite single crystals through droplet-assisted self-alignment

Patterned arrays of perovskite single crystals can avoid signal cross-talk in optoelectronic devices, while precise crystal distribution plays a crucial role in enhancing device performance and uniformity, optimizing photoelectric characteristics, and improving optical management. Here, we report a strategy of droplet-assisted self-alignment to precisely assemble the perovskite single-crystal arrays (PSCAs). High-quality single-crystal arrays of hybrid methylammonium lead bromide (MAPbBr3) and methylammonium lead chloride (MAPbCl3), and cesium lead bromide (CsPbBr3) can be precipitated under a formic acid vapor environment. The crystals floated within the suspended droplets undergo movement and rotation for precise alignment. The strategy allows us to deposit PSCAs with a pixel size range from 200 to 500 micrometers on diverse substrates, including indium tin oxide, glass, quartz, and poly(dimethylsiloxane), and the area can reach up to 10 centimeters by 10 centimeters. The PSCAs exhibit excellent photodetector performance with a large responsivity of 24 amperes per watt.

Photocurrent density distribution imaging results before (A) and after (B) the repair of the dead pixel.The bias voltage was 3V and the light intensity was 3.46 mW cm -2 .After repairing, the photocurrent density of dead pixel increased from 1.5  10 -4 to 5.52  10 -4 A cm -2 with no obvious difference from the surrounding pixels.

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Fig. S2.Crystallization results when isopropanol was selected as the anti-solvent.(A and B) Microscopic images of MAPbBr3 within the suspended droplets with the molar ratio of MABr to PbBr2 of 1.0 (A) and 1.5 (B).(C) Microscopic image of MAPbBr3 crystals after solvent complete evaporation in (B).

Fig. S3 .
Fig. S3.Crystallization results with different evaporation rates of FAH and ambient temperatures.(A and B) Microscopic images of MAPbBr3 within the suspended droplets (A) and MAPbBr3 after solvent complete evaporation (B) with rapid evaporation rate of FAH.(C) Microscopic image of MAPbBr3 grown at 50℃. (D) Microscopic image of MAPbBr3 within the suspended droplets grown at room temperature with controlled FAH evaporation rate.

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Fig. S4.SEM images of as-grown MAPbBr3 arrays (A) and MAPbCl3 arrays (B) on the square prisms (top view).

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Fig. S5.Fluorescence microscope images of as-grown MAPbBr3 arrays (A) and MAPbCl3 arrays (B) (which are excited with a pulsed 405 nm laser).

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Fig. S6.SEM image of the MAPbBr3 crystal at the center of the micropillar (side view).

Fig. S8 .
Fig. S8.The shape of the droplet altered by the crystal.(A and B) Microscopic images of the suspended droplet without (A) and with (B) a crystal.(side view).The dotted red lines outline the droplets.

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Fig. S11.Crystal arrangement results on the pentagonal prisms and hexagonal prisms.(A and B) Microscopic images of the suspended droplets (A) and MAPbBr3 arrays (B) on the pentagonal prisms.(C and D) Microscopic images of the suspended droplets (C) and MAPbBr3 arrays (D) on the hexagonal prisms.

Fig. S13 .
Fig. S13.The dependence of crystal size on the square prism size.(A) The dependence of crystal thickness on the square prism width.(B) The dependence of crystal width on the volume of precursor droplet.

Fig. S14 .
Fig. S14.Repair of dead pixels.(A) Microscopic image of the as-grown MAPbBr3 arrays with 10 rows and 10 columns.The red dotted circles show the crystals with uncontrollable shape and position.(B) Microscopic image of the repaired MAPbBr3 arrays.

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Fig. S17.Photocurrent density distribution imaging results before (A) and after (B) the repair of the dead pixel.The bias voltage was 3V and the light intensity was 3.46 mW cm -2 .After repairing, the photocurrent density of dead pixel increased from 1.5  10 -4 to 5.52  10 -4 A cm -2 with no obvious difference from the surrounding pixels.